Such as in this AU the car crash David survived yet Emily was stuck in the car which she didn't survive. This made he fill guilt & PTSD for a long time as he never recovered yet still hold on for the love of his wife Karen & son Navin. Later he with his family would arrive to Karen's grandpa's home & later start the misadventures with the whole Stonekeeper electric boogaloo where he might at first be easily controlled by Ikol though would find out the solution.
He might be glad his son Navin not just having great leadership but also able to be the boyfriend with the girl Alyson Hunter.
Yet I prefer another AU where this version (Emily's universe) of Earth's various nation leaderships (mainly Superpowers the USA, China & Russia) after learning this info of the Shadows' existence when Silas (who also made them, Ikol too) arrived to Earth being captured & interrogated led to the nations agree to set up loads of defense plans plus find as much galactic allies as possible to wipe them off.
Although they let Silas leave to start new life with having his family exists, he's been keep at close eye to make sure nothing funny is going on.
Before Silas death he'll contact his family & Earth's govs that the plans are drawn to stop the Shadows once & for all where the top secret black ops task force group to assist Emily, Navin, Karen & the Resistance allies (on & outside Alledia) to finish this once and for all.
As for the other AUs are up to u all to decide.